BMW E34 instrument cluster display and gauge faults
Why does the E34 speedometer jump or not work?
First check the speed sensor connector and wires: an oxidised connector or a sensor wire broken at the base of the connector causes jumping or stopping. The fault can also be in the cluster capacitors. Clean the connector and check the wires.
Why do the cluster displays or gauges go dark?
Electrolytic capacitors and internal batteries in the cluster are a typical fault in the E34. Replacing the capacitors is a cheap and easy repair that is worth trying first, but it does not help in all cases. Also check the cluster connectors. Replacement requires taking the cluster apart.
Is the consumption gauge needle rising to the stop a fault?
No. Below 20 km/h the consumption gauge does not measure, so the needle can rise to the stop when slowing down, and it falls back when the revs drop below 1000 rpm. At idle when stationary the needle can also disappear.
Why do the gauges read wrong after the cluster has been replaced?
The cluster's coding plug determines, among other things, how the tachometer and the consumption gauge work. A wrong plug or one from another car can give a wrong rev reading, consumption gauge errors or a temperature gauge that does not work. Use the plug from the car's own cluster.